U.S. Publication No. 2009/0298172 to Wheeler, hereby incorporated by reference in its entirety, describes a histoprocessing technique. Referring to prior art FIG. 1, the histoprocessing instrumentation 25 described in U.S. Publication No. 2009/0298172 includes a hermetically sealable, pressure and temperature regulated reaction container 11 sized to hold a number of tissue samples 26. The reaction container is connected by a network of conduits and valves to a source of melted Paraffin constituted by a Paraffin makeup vessel 27, to a source of dissolving compound in the form of a solvent regenerator 28 drawing from a chemical tank 29, to a solvent pump 30, to a vacuum pump 31, and to an overflow reservoir 32. The solvent pump is designed to operate over a wide range of temperatures and pressures.
As shown in prior art FIG. 2, the solvent regenerator 28 of U.S. Publication No. 2009/0298172 is connected to a solvent distillation assembly 33 including an accumulator 34, a recirculation pump 35 and a condenser 36. A thermocatalytic oxidizer 37 is used to breakdown waste gases into water and carbon dioxide. A carbon bed device could be substituted for the oxidizer. The waste material extracted from the used dissolving compound is sent to a waste tank 38. A process heater 39 (FIG. 1) is provided between the solvent pump 30 and the reaction vessel 11. A heat exchanger 60 consisting of a 500 watt, explosion-proof bulb is mounted inside the solvent regenerator 28. A jacket heater 40 surrounds the solvent regenerator 28. A similar jacket heater 65 surrounds the reaction container 11. A series of snubber protected pressure sensors 64, 72 and 73 are connected to various areas of the system to regulate pressures.
Valves 41-59, and the pumps 30, 31 and 35 are controlled by a programmable electronic unit 41 according to techniques well known in the industrial process arts.
U.S. Publication No. 2009/0298172 describes a process of treating tissue specimens. Tissue specimens are loaded into a stainless steel or polymer constructed basket, and then placed into the reaction container 11. The container cover is then closed and latched. Proximity sensors detect the lid and the process starts. Valve 49 opens and the vacuum pump 31 is started. The pressure of the system is reduced below ambient atmospheric pressure. Valve 49 closes, the vacuum pump is turned off and the system comes to pressure equilibrium. If this condition is not achieved within one minute, a leak is assumed, and the system is shut off.
Preconditioned dissolving compound is transferred from the solvent regenerator 28 to the reaction container 11. Valves 43, 44 and 45 are opened and the reactor jacket heater 65 is energized. The solvent pump 30 and heater 39 are energized. Hot compound fills the reaction container until a solvent level detector switch 67 is triggered. The pressure in the reaction container is regulated by opening valve 47 and the reactor's pressure sensor 64. Valve 45 closes and valve 42 opens. The dissolving compound is recycled and heated in the closed loop consisting of valves 42, 43, and 44, heater 39, solvent pump 30, and the reaction container 11. At this time, the solvent pump 30 is used to pump up the reactor 11 to an operating pressure as high as about 3.3 bars (50 psig).
Specimens are exposed to the dissolving compound for 10 to 30 minutes. During this exposure, cellular solutes are extracted, (e.g., water, lipids, etc.), and replaced with a mixture of liquid Paraffin and the low molecular hydrocarbons of the compound. Valve 42, 43 and 44, the process heater 39, and the solvent pump 30 are turned off. Hot dissolving compound is transferred from the reaction container 11 to the solvent regenerator 28. The transfer path includes valves 42, 43, and 44. Valve 47 is opened between the reaction container and the solvent regenerator in order to equilibrate pressure. The transfer lasts until the container's low level indicator switch 63 is reset. At this time, valve 42 is closed and the compound is recycled and reconditioned as later explained. The reaction container 11 is next flooded with liquid Paraffin as follows. Valves 42 and 49 open, the vacuum pump 31 is turned on. Liquid Paraffin flows into the container until the level indicator switch 67 is triggered. A high level indicator switch 68 in the container acts as a fail-safe device. At this time valve 42 is closed. The saturated specimens are then subjected to a vacuum to extract volatiles.
The pressure in the container is further reduced to evaporate all dissolving compound present. The diffusion pump 66 is used to reduce pressures to less than 1 torr. Vacuum is applied until pressure equilibrium is achieved, e.g. about 0.9 to 0.99 At. (−27 to −29.91 inches Hg), depending upon solvent. Once equilibrium is reached, all volatile solvent molecules have been removed from the reaction container and specimens. The process is allowed to continue for an additional 10 to 30 minutes depending upon total mass of specimens.
The vacuum system consists of the vacuum pump 31, the diffusion pump 66, and the overflow vessel 32 equipped with a proximity sensor 71, and an isolation valve 49. The overflow vessel acts as an additional fail-safe device in case of failure of the high level indicator switch 68. The air makeup valve 50 is provided to dilute gases prior to entering the thermocatalytic oxidizer 37 and to supply cooling gases to the reaction container during cool down cycles. The pressure sensors 64, 72 and 73 are connected to the control unit 41 in order to monitor all processes of the instrument. Snubbers are employed to prevent liquid from entering the pressure sensors.
In a final step, the Paraffin is returned to the Paraffin makeup vessel 27 as follows. Valves 42, 49 and 50 are opened and the vacuum pump 31 is turned off. Cooling air is drawn through valve 50 and routed to the reaction container 11. Paraffin is gravitated to the Paraffin makeup vessel 27. During this time, the specimen temperature drops below the Paraffin melt point. The lid of the container opens, the specimen tray is withdrawn and the specimens are extracted and separated.
U.S. Publication No. 2009/0298172 describes that the following alternate batch solvent blending process may be practiced to prepare a Paraffin-loaded dissolving compound.
Referring to prior art FIG. 2, the reaction container 11 is hermetically sealed. A measured volume of Paraffin-free based solvent is drawn from the chemical tank 29 through a coupler 75 and transferred to the solvent regenerator 28 where it is heated to 60° C. The jacket heater 40 of the solvent regenerator and the vacuum pump 31 are energized. A normally closed control valve 42 is opened and liquid Paraffin is transferred from the Paraffin makeup vessel 27 to the reaction container 11 until a Paraffin level detector 62 inside the reaction container is triggered. At this time, the control valve 42 is closed, and the vacuum pump 31 is stopped. Control valves 43, 44, and 45 are opened and solvent is transferred from the solvent regenerator 28 to the reaction container 11. When the level detection switch 67 in the reaction container is triggered, the solvent pump 30 is stopped. At this point, all control valves are positioned to create the loop configuration described earlier. The process heater 39 and the solvent pump 30 are energized. The solvent and Paraffin are allowed to blend for about ten minutes into the final dissolving compound. The circuit is reconfigured to transfer the entire blended compound to the solvent regenerator 28. The reaction container 11 is evacuated. The system is now ready to process specimens.
A process for solvent recovery and regeneration is also described in U.S. Publication No. 2009/0298172 and illustrated in prior art FIG. 2. The objective is to recover, purify, and re-use extraction solvents by isolating and filtering cellular solutes from the dissolving compound for waste disposal. U.S. Publication No. 2009/0298172 also describes a technique for dissolving compound waste gas disposal.
U.S. Publication No. 2009/0298172 describes temperature and pressure preconditioning of the dissolving compound as follows.
The cellular solute extracting mixture is loaded into the chemical tank 29. A bottle coupler 75 provides a connection for solvent transfer and venting. Valves 46, 44 and 43, are open and the solvent pump 30 transfers mixture into the solvent regenerator 28. Valves 47 and 49 are opened to provide a path to the thermocatalytic oxidizer 37. Once the mixture is transferred from the chemical tank to the solvent regenerator, valves 46 and 47 close. The transfer is monitored by level control switches. Valve 45 is opened and the mixture is heated in the regenerator loop, using the process heater 39 and the regenerator jacket heater 40.
Vent gases are delivered to the thermocatalytic oxidizer 37 for oxidation to carbon dioxide and water as follows. Valve 50 is opened, the vacuum pump 31 is energized. Waste gases are delivered to the oxidizer. Once the inline thermal conductivity detector detects room conditions, valve 49 and 50 close and the vacuum pump is turned off. The mixture is heated to the desired temperature and pressure, e.g. 60° C. and about 0.8 bars (12 psig). It should be noted that the solvent regenerator operating conditions are flexible, and that it can heated from 20 to 100° C. and pressurized to from 1 to about 3.5 At. In addition, the variable flow and pressure solvent pump will operate equally over a wide range of temperatures and pressures. A flow orifice may be placed on the discharge to insure proper pump lubrication. Also, it is worth noting that the Paraffin present in the solvent also provides lubricating properties for pumps and valves.